A wireless metropolitan area network standard for the broadband wireless access (BWA) is defined by the IEEE 802.16, in which different physical layer techniques are defined for different frequency bands. The standard is mainly applied in the house, small office/home office (SOHO), remote worker, and small enterprise (SME) oriented markets.
The IEEE 802.16 media access control (MAC) supports a severe subscriber environment, dealing with an application environment with hundreds of subscriber on each channel, and supporting continuous traffic and burst traffic. It is provided with an asynchronous transfer mode (ATM) convergence sublayer and a packet convergence sublayer. Being processed by the convergence sublayer, a plurality of high-level data units is packed as a (MAC) protocol data unit (PDU) for sending, thereby achieving a protocol transparency for the ATM, IP, and Ethernet service.
The worldwide interoperability microwave access (WiMAX) technique is a broadband wireless access technique based on the IEEE 802.16 air interface protocol, and defines the terminal mobility capability supports. As shown in FIG. 1, it is a schematic diagram of a WiMAX paging network. As seen from the FIG. 1, the paging network mainly includes a mobile station (MS), an access service network (ASN), and a connectivity service network (CSN).
The MS is provided for the subscriber to access the WiMAX network.
The ASN defines a network function collection for providing wireless access services for the WiMAX subscriber. The ASN includes a base station (BS) and an ASN gateway (ASN GW). The main functions of the BS include providing an L2 connection between a BS and an MS, a radio resource management, and so on. The main functions of the ASN GW include providing a client function for the MS authentication, authorization, and accounting functions, and providing a relay function (e.g., IP address assignment), or intra-ASN handover of the L3 information for the MS.
The CSN is defined to provide an IP connection service for the WiMAX subscriber. The main functions provided by the CSN include IP address assignment for the MS, Internet access, an authentication, accounting, and authorization (AAA) server or an AAA proxy, a user-based authorization control, and so on.
Due to the movement of an MS, and connection relationships of the network structure, the handover scenarios are diversified. As shown in FIG. 2, a handover process through a centralized control manner generally requires three steps.
1. The MS communicates with the current serving BS via an air interface, and the serving BS communicates with the current serving ASN-GW1, as shown by the state indicated by the line (1) in FIG. 2.
2. When the MS's movement or resource optimization for the network side cause handover process, and the MS is handed over, the MS communicates with a target BS. The target BS and the serving BS communicate with an identical ASN-GW1, merely the interface R6 needs to be relocated, and the interface R3 remains unchanged during the handover motion, as shown by the state indicated by the line (2) in FIG. 2.
3. When the MS's movement or resource optimization for the network side cause handover process, and the MS is handed over, the MS communicates with the target BS. The target BS communicates with a target ASN-GW2, the original interfaces R6 and R3 both need to be relocated. The signaling interface from the core network to the MS is relocated to the target ASN-GW2. The interfaces involved include R3, R4, and R6. The state indicated by the line (1) directly handovers to the state indicated by the line (3) in FIG. 2.
4. Corresponding to the step 2, after the handover indicated in step 2 is performed, the communication line is shown as the line (2) in FIG. 2. When resource optimization for network side causes a handover process, the state indicated by the line (2) directly handovers to the state indicated by the line (3) in FIG. 2, merely R3 interface is involved, without affecting the air link between the MS and the BNS, and R6 air interface. After the handover is complete, the signaling interface with the core network is entirely relocated to the target BS and the target ASN-GW2, as shown by the state indicated by the line (3) in FIG. 2.
The handover mentioned in the invention not only includes air interface handover caused by an MS's mobility, but also the subscriber air interface handover initiated by the network side and the handover process characterized by mere R3 link handover when resource optimization for the network side occurred. In the network shown in FIG. 2, the state indicated by the line (2) is taken as an initial state, the ASN GW1 or the ASN GW2 may trigger the handover merely involving R3 link, which does not affect the air link between the MS and the BS, and the air link between the BS and R6 of the ASN GW.
In the network shown in FIG. 2, the BS is a logic entity, which generally includes a MAC and PHY entity processing, a service flow management (SFM) entity, a handover (HO) function entity, a data path function entity, a context function entity, and one or more of those function entities.
The ASN-GW is a logic entity, which generally includes an authenticator, a mobile IP (MIP) client, a foreign agent (FA), a paging controller (PC), a service flow authorization (SFA), a relaying handover function entity, a data path function entity, a context function entity, and one or more of those function entity.
FIG. 3 shows schematic relationships between the above various function entities. The context function entity is divided into a context client and a context server, which are adapted to maintain and manage the session context and other information of the MS. Usually, during the handover process, in order to keep the continuity of the MS session before and after the handover, essential context information should be transmitted at the serving BS side and the target BS side.
1. The current solution mainly defines the following content for the MS session information context:
(1) MS/Session Information:
MS network access identification (MS NAI);
MS MAC address;
Anchor ASN-GW identification associated with the MS;
(2) List Associated with the Service Flow Identification (SF ID):
Service flow (SF) classifier rule;
SF quality of service (SF QoS);
Connection identification (CID) (associated with the SFID);
Data path tagging (ID) information;
Etc.;
(3) R3 (Reference Point 3) Related Information:
Home Agent IP address;
Care-of address (CoA);
Dynamic Host Configuration Protocol (DHCP) server address;
AAA server address;
R3 link status details (to be discussed (TBD));
(4) Security Information:
Security information related to PKMv2;
Security information related to Proxy MIP (if used);
The actual details of the content and elements are TBD.
2. The current solution defines two primitives about MS context conveying, i.e., Context Request message and Context Report message, and involves two function entities, i.e., a context function entity (Context Client) for requesting the MS context and a context function entity (Context Server) for storing the MS context.
(1) Context Request Message
This primitive is mainly provided for one network entity to request specific MS's session information from another network entity.
(2) Context Report Message
This primitive is provided to actively report the MS session context information, or respond to the context request message.
The session information report may be sent to a corresponding network entity as a part of the handover control primitive in a manner of active reporting.
The above technique causes that the MS context information lacks of various anchor function entities identification information acting on the MS, so a correct addressing of these logic entities by the MS cannot be ensured during the handover process.
Furthermore, specific occasion and process of the MS context conveying are not described in the above technique, different local policies of the source and destination ends are not considered during the MS context conveying process, and the destination end may update some MS context according to its own local policy during the conveying process. Furthermore, the hierarchy of the MS context conveying during the handover is not considered in the above solution.